The number can be seen on the patent document under INID code 11. The format of this number identifier may vary depending on the issuing office and the type of patent application. However, the most general outline of all patent numbers contains a combination of some or all of the following sections (see also the image below). This general format can change during the life time of the patent for different reasons.
Patent offices may change (have changed) the format of its patent numbering system over the years. Therefore, one may see a different patent number format from the same patent office depending on the time period when the patent was issued. Also note that some patent offices may use a different format after the patent is granted as compared to when the patent application is under examination (e.g. the US patent office), while others (e.g. EPO or China) keep the same number series but use the kind code to distinguish them apart.
A patent number indicates that a product or invention is protected by a patent application which means that the patent owner has all the rights to this invention and can stop others from using it without a license. It is therefore usual to find patent numbers inscribed on a commercial product or in the product documentation to indicate ownership of the rights and to warn off others from unlawfully copying the solution.
Following Table shows the currently used patent number formats from selected patent offices. For earlier number systems please consult the relevant patent office.